e safe unwatched. He was provided with a spare patent padlock
and key, of the sort you used on that black box, and his confederate had
drilled him in the trick of breaking that particular sort of padlock
open, with other spare specimens. He got his opportunity this morning."

"Only this morning?"

"This morning, I think, else we should never have got these bonds back,
nor even have heard of them again. I think you said you were engaged
with a client for half an hour?"

"Yes, from about half-past ten to eleven."

"That was his chance, and he took it. He broke the padlock, took out the
bonds, substituted the dummies he had already prepared in his own desk,
and locked the box again with the new padlock. Meantime Hunt had paid a
deposit, pending references, on the office below--the nearest empty
room. Of course, he wouldn't get the key until the tenancy was finally
accepted--which he never intended it should be. But he easily arranged
to have the door left unlocked for a day or two, on some convenient
excuse--arranging decorations, or what not. And the bill was taken down,
so that prospective and prospecting tenants were kept away. The bonds
being stolen, Henning took the first opportunity of carrying them to the
empty office--probably piecemeal--a thing he could easily manage almost
under your nose, before you were aware of your loss. There he was to
conceal them, either in the chimney, under the boards, or in the
ventilator, as he might find convenient--and he found the ventilator
most convenient. Then he was to apprise his confederate of the fact that
the robbery had been effected in order that Hunt might come and quietly
fetch the plunder away. The message was to take an ingenious form. Hunt
was to have a fellow waiting about in the street, and as soon as Henning
could get out--say to lunch--he was just to _send the key_ by this
messenger--the key with which he had locked the new padlock on the black
box. You see the advantages of that simple arrangement. First, the key,
which is evidence, is got rid of in a safe and effectual way--a thing
that couldn't be done as well by merely flinging it away on or near the
premises, where it might be found. Next, the message is perfectly
secret--the messenger could never guess what the key meant, nor could
any other person not in the confederate's confidence. And, at the same
time, the key tells all that is necessary; the robbery has been
effected--come and remove the plunder.